Update prepare() method on Action subclasses.

Fixes handle()-related strict warnings such as "Strict Standards:
Declaration of AdminPanelAction::prepare() should be compatible with
Action::prepare(array $args = Array)

Ref. #190

plugins/Bookmark/actions/apitimelinebookmarks.php

@@ -57,7 +57,7 @@ class ApiTimelineBookmarksAction extends ApiBareAuthAction
      *
      * @return boolean success flag
      */
-    function prepare($args)
+    function prepare(array $args = array())
     {
         parent::prepare($args);
 

plugins/Bookmark/actions/bookmarkforurl.php

@@ -59,7 +59,7 @@ class BookmarkforurlAction extends Action
      *
      * @return boolean true
      */
-    function prepare($args)
+    function prepare(array $args = array())
     {
         parent::prepare($args);
 

plugins/Bookmark/actions/bookmarks.php

@@ -60,7 +60,7 @@ class BookmarksAction extends Action
      *
      * @return boolean success flag
      */
-    function prepare($args)
+    function prepare(array $args = array())
     {
         parent::prepare($args);